Backplane based computer systems comprise one or more circuit boards plugged into one or more sockets of a backplane. The computer system in one example comprises a telecommunication system server. The backplane communicatively couples the circuit boards. The circuit boards comprise one or more clocks. The clocks in one example run more efficiently when synchronized. For example, a frequency signal travels from one of the circuit boards to one or more of the other circuit boards through a signal path in the backplane. The circuit boards employ the frequency signal to maintain clock synchronization of the clocks. Communication errors may result if the circuit boards fail to maintain the clock synchronization.
Clock signals require a redundancy to increase fault tolerance. For example, if a single clock signal source or distribution signal fails, the remainder of the system must continue to function with redundant clock signal sources and distribution signals. The clock source in one example is simplex. As one shortcoming, a single failure in the clock source can disable the entire system.
A first circuit board in one example comprises a clock signal source. The clock signal source generates the frequency signal. The clock source in one example comprises an Ethernet connection, a T1 connection, or a precision oscillator. The first circuit board sends the frequency signal to the signal path of the backplane. The frequency signal comprises a fixed signal on the signal path of the backplane. For example, the signal path always carries the frequency signal from the clock signal source to synchronize the clocks of the other circuit boards. As one shortcoming, the signal path always carries the frequency signal from the same clock signal source.
The clock signal source in one example is coupled to a processor component. The processor component modifies the frequency signal from the clock signal source. For example, the processor component scales the frequency signal by a factor before the circuit board sends the frequency signal to the signal path of the backplane. The clock signal source in one example is hard wired to the processor component. As one shortcoming, the clock signal source always sends the frequency signal to the same processor component.
Thus, a need exists for an increased ability to handle frequency signals from any of a plurality of clock signal sources. A further need exists for an increased ability to handle a plurality of processor components.